1. Field of the Invention
The present invention relates generally to a liposuction cannula system and, more particularly, to a liposuction cannula system having a vent hole for increasing the mass flow rate of fatty tissue and other debris through the cannula system.
2. Background Description
Liposuction is a well known surgical procedure for surgically removing fat tissue from selected portions of a patient""s body. That is, liposuction may be used, for example, to contour selected body parts such as the abdomen, buttocks, hips, thighs and the like. Liposuction is also known as suction lipectomy, lipolysis and body contour surgery or body sculpting surgery.
To perform this surgical procedure, a hand-held instrument (e.g., a cannula) is inserted through the patient""s skin into the fat pockets. Once inserted below the skin and into the fat pockets, the cannula is moved around to break up the fat cells and pieces of the fat tissue are then aspirated through small openings along the sides or tip of the cannula by vacuum pressure from a syringe or pump. The fat tissue is then forced through a central lumen in the cannula to a tissue canister placed in-line with the cannula and the suction source.
The cannula is conventionally a thin tube with an aspirator tip at a remote end. The aspirator tip may include small openings at the sides or end of the tip and is designed to create passages between the tissue and the central lumen of the cannula. The central lumen is then in fluid communication with a suction source so that tissue and fluids can be aspirated or suctioned through the cannula and into the tissue cannister. The suction causes the tissue to be pulled into the openings at the aspirator tip of the cannula. As such, the cannula servers two purposes; namely, the cannula is used to crush, tear, or avulse the fatty tissue and then suction the fatty tissue through the central lumen to aspirate the tissue fragments and fluids from the operative site.
It has been found, however, that conventional cannula systems do not provide adequate mass flow rates for the fatty tissue to pass through the central lumen in order to adequately aspirate the fatty tissue and other fluids from the surgical site. This is mainly due to the fact that a seal is created between the outer surface of the cannula about and along its length and the fatty tissue which prevents the flow of any ambient pressure fluid, such as air, to the operative site about the tip of the cannula. Thus, when suction is applied by a vacuum or other source, the seal prevents the flow of any ambient pressure fluid to the operative site about the tip or the cannula and hence the pressure about the tip of the cannula quickly drops to the pressure of the suction source. This pressure is significantly below the ambient pressure which, in combination with the seal, reduces the suction capacity of the cannula system. In this case, the fatty tissue fragments and other fluids move very slowly through the cannula and suction tubing.
To avoid this problem, the tip of the cannula may be withdrawn from the patient so that the seal is broken and the tip or side openings are exposed to ambient air pressure. To accomplish this, however, the surgeon has to insert and remove the cannula from the surgical site many times during a surgical procedure. This may lead to further trauma at the surgical site.
To avoid inserting and removing the cannula from the surgical site to thus increase the mass flow rate of the fatty tissue, other systems have provided a single hole or vent in the hub portion of the cannula. The hole provides an air passage into the system and thus aids in the suctioning of the fatty tissue and other fluids. These systems, however, typically require a surgeon to regulate the air flow through the hole by manipulating the surgeon""s finger over the hole.
The use of a vent hole in prior art cannulas is both cumbersome and inefficient. With regard to the former shortcoming, the surgeon must both manipulate the cannula and, at the same time, attempt to regulate the air flow which is delivered through the hole. As to the latter shortcoming, the surgeon cannot regulate the air flow through the hole with any accuracy. These same systems do not provide a mechanism for allowing the airflow to be delivered parallel to the liquid flow and away from the cannula wall. That is, the airflow in these systems are introduced into the lumen in a turbulent flow thus disrupting the liquid flow therein. Also, these systems have not provided the vent holes, either in position or size, to maximize the suctioning capabilities of the cannula system, nor do they make any accommodations for clogging of the hole, itself.
Accordingly, there remains a need to provide a cannula system which provides a mechanism to maximize the suctioning of the fatty tissue and other debris and fluid. Also, there remains a need to provide a system which is capable of introducing air flow into the lumen in a path that is parallel to the liquid flow and away from the cannula wall, both of which would further maximize the mass flow rate of the fatty tissue, liquid and other debris through the cannula.
It is therefore an object of the present invention to provide a cannula system which is capable of increasing the mass flow rate of fatty tissue, liquid and other debris flowing through the lumen.
It is another object of the present invention to provide a cannula system which has a mechanism for providing airflow into the lumen of the cannula parallel to the fatty tissue, liquid and other debris flowing therethrough.
It is still a further object of the present invention to provide a cannula system which provides airflow into the lumen of the cannula and away from the interior wall of the cannula.
It is also a further object of the present invention to provide a cannula system which is capable of introducing airflow into the lumen in a non-turbulent manner.
In one aspect of the invention, a cannula system has a tube having a bore extending along a length thereof. An assembly is connected to a proximal end of the tube and an aspirator tip having openings is positioned at another end of the tube remote from the assembly. A vent hole is positioned along the length of the tube away from the assembly. The vent hole has a diameter of approximately between 0.012 and 0.0135 inches and allows air to flow within the bore of the tube. In embodiments, the vent hole is positioned at substantially a center of the tube to prevent clogging thereof.
In another aspect of the present invention, a cannula system includes a tube having a bore extending along a length thereof and an aspirator tip having openings positioned at a remote end of the tube and in fluid communication with the bore. A vent hole is positioned along the length of the tube and a plug is positioned within the vent hole. The plug has an air passageway in fluid communication with the bore.